In addition to microelectromechanical system (MEMS) fixed or static fractal capacitors, fractal capacitors may be advantageously utilized with MEMS variable capacitors. MEMS variable capacitors have been researched for nearly 15 years. With respect to electrostatically actuated MEMS variable capacitors specifically, there are two main types of structures, namely the parallel plate type and the comb drive type.
The parallel plate type provides a theoretical maximum tuning range of 1.5:1 because it is limited by the pull-in effect; it also provides a nonlinear capacitance tuning response. On the other hand, the comb drive structure provides better linearity, suppresses the effect of pull-in, and enhances the tuning range beyond the 1.5 limit as present in the parallel plate type. However, in order to obtain usable capacitances, a very large area of the chip/die must be consumed which is not always possible in current technology where the real estate on wafers is very expensive.